Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Master Credit Facility	Mar. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000
Commercial paper	(2,540,000,000)
Outstanding letters of credit	(49,000,000)
Tax-exempt bonds	(81,000,000)
Coal ash set-aside	(500,000,000)
Available capacity under the Master Credit Facility	4,830,000,000
Duke Energy Carolinas
Line of Credit Facility [Line Items]
Facility size	1,500,000,000
Commercial paper	(300,000,000)
Outstanding letters of credit	(4,000,000)
Coal ash set-aside	(250,000,000)
Available capacity under the Master Credit Facility	946,000,000
Duke Energy Progress
Line of Credit Facility [Line Items]
Facility size	1,250,000,000
Commercial paper	(275,000,000)
Outstanding letters of credit	(2,000,000)
Coal ash set-aside	(250,000,000)
Available capacity under the Master Credit Facility	723,000,000
Duke Energy Florida
Line of Credit Facility [Line Items]
Facility size	800,000,000
Commercial paper	(167,000,000)
Available capacity under the Master Credit Facility	633,000,000
Duke Energy Ohio
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(243,000,000)
Available capacity under the Master Credit Facility	357,000,000
Duke Energy Indiana
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(150,000,000)
Tax-exempt bonds	(81,000,000)
Available capacity under the Master Credit Facility	369,000,000
Piedmont Natural Gas
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(265,000,000)
Outstanding letters of credit	(1,000,000)
Available capacity under the Master Credit Facility	334,000,000
Duke Energy (Parent)
Line of Credit Facility [Line Items]
Facility size	2,650,000,000
Commercial paper	(1,140,000,000)
Outstanding letters of credit	(42,000,000)
Available capacity under the Master Credit Facility	1,468,000,000
Duke Energy (Parent) | Proceeds loaned to subsidiary registrants
Line of Credit Facility [Line Items]
Commercial paper	$ (625,000,000)